High voltage safety switch



' Feb. 26, 1946. F. E. RUNGE HIGH VOLTAGE SAFETY SWITCH Filed May 1,1944 IN V EN TORJ anli'l? QM ATTOEWEX Patented F eb. 26,1946

UNiTEo "rs AT NT FFHCE I 2.395.683 men VOLTAGE SAFETY swrrcn Frank E.Range, Haddon Heights, N. J., assignor to Radio Corporation of America,a corporation of Delaware Application Mi. 1, 1944, Serial No. 533,601

9 Claims.

The present invention relates to electron microscopes and other higvoltage electrical apparatus, and more particularl to an assemblyoperated by the opening of a door 'or doors of the housing for the highvoltage units.

Some of the objects of the present invention are: to provide a safetygrounding means for high .sembly in response to the opening of a door ordoors; to provide a compact, positive and foolproof mechanism forgrounding housed high voltage units when a door or doors of the housingis opened; and to provide other improvements as will hereinafter appear.

, In the accompanying drawing,

Figure 1 represents a longitudinal section, in

part, of one form of grounding mechanism embodying the presentinvention;

Figure 2 represents a section on line II-II Fig. 1;

Figure 3 represents a fragmentary plan of the plunger parts in positionas restrained by the closed doors;

Figure 4 represents the plan of Fig. 3 showing the position of the partswhen opening of the left door; I

Figure 5 represents a section on line VV of Fi Figure 6 representsasection on line VI-VI of Fig. 4;

Figure 7 represents a section on line VIIVII of Fig. 3;

- Figure 8 represents a section on line VIII-VIII of Fig.4; and

Figure '9 represents a detail perspective of one set of the ground rodactuating'means.

Referring to the drawing, one form of the pres ent invention is shownmounted on the rear wall 9 of the housing for the high voltage units ofan electron microscope, and in position to be controlled by the twoopposite doors l0 and I I which serve to gain access to the interior ofthe housing.

For contacting conductors, condensers or other high voltage parts, thereis provided a plurality of grounding rods l2, usually of differentlengths released by the in order to reach parts at different distancesfrom the wall 9. Each rod l2 has one end looped about an actuatingsleeve i3, at spaced interval for free turning movement thereon, and isheld against. lengthwise movement on the sleeve lit by a pair of collarsl4 and I5 which are fixed to the sleeve l3 by set screws i6 or the like.The collar i4 is provided with a pick-up pin i1 pro- .iecting laterallyand parallel to the sleeve i3 to engage one side of the adjacent rod i2,and the collar i5 has a like pick-up pin it projecting laterally andparallel to the sleeve to engage the oppositeside of the same rod |2.-Thus turning of the sleeve i3 in a clockwise direction, as seen in Fig.9, will cause the pins I to flip the rods i2 clockwise considerablytoshift them past the dead center of the sleeve so that each rod is forcedagainst, or finally falls by gravity against, its adjacent conductor. Toreturn the rods l2, the sleeve i3 is turned counter-clockwise and thepins it then pick up the respective rods l2 and re-- turn them tocontact with the wall 9. On this return movement the pins l8 remain incontact with the rods l2 to hold them against the wall 9.

It is important that the collars l4 and i 5 be rotationally adjusted andfixed upon the sleeve l3,

so that the pick-up pins i1 and it have a predetermined arc of travel topick up the rods l2 in the required manner.

For imparting rotary movement to the sleeve l3, it is supported by andis freely rotatable on a tube 8, and receives its motion by means of acam followeror pin 20 fixed to a plunger 2! and projecting radiallytherefrom to traverse a cam slot 22 in the tube 8 and enter a linearslot 23 in the sleeve i3. The slot 23 is parallel to the axis of thesleeve l3 and has a uniform width to slidably receive the cam followeror pin 20. The cam slot 22 is in the form of a spiral across thejuxtaposed face of the tube 8. It will thus be seen that relativemovement between the pin 20 and the tube 8 will shift the pin 20 againstone or the other side of the slot 23, depending upon its direction oftravel, and thus turn the sleeve H as required to shift the rods 12 togrounding position or opposite thereto.

For actuating the pin 20, the plunger 2! is of a length to project fromone end of the tube 8 into the path of the door Ii, so that as thelatter is closed it will contact the end of the plunger 2| and shift itaxially of the tube 8 (to the left as seen in Fig. 1 thereby to causethe pin 20 to turn the sleeve I 3). Rotation of t'he sleeve i3 from theopposite end of the mechanism is accor iplished by the axial movement ofa thrust-pin 24 permitting endwise fixed to and projecting radially froma plunger 25 to pass with a snug fit through a hole in the tube 8 andtraverse an opening 28 in the sleeve i3. This opening 26 is of suchdimensions as to allow unrestricted linear and rotary motion of the pin24 with respect to the sleeve l3. The free end of the thrust-pin 24 isarranged to ride in a slot 21 formed between two superposed lugs 28fixed to the wall 9. The slot 21 is longer than the maximum stroke ofthe thrust-pin 24 and its function is to prevent turning of the tube 8while movement thereof. The plunger 25, firmly fixed in the tube 8,projects from the end of the sleeve [3 into the path of the door l0, sothat as the latter is closed it will contact the end of the plunger 25and shift it axially of the sleeve l3.

For maintaining the plungers 2| and 25 projected for contact with therespective doors l8 and H, a compression spring 29 is interposed betweenthe opposed ends of the two plungers and functions to propel one or theother, or both outwardly when either or both doors are opened.

In order to support the assembly on the wall 9, brackets 30, in the formof apertured angle irons 32, carrying bushings 33 to receive guide therespective plungers 25 are provided. These bushings 3| allow freeturning movement of the sleeve 13 as will be understood.

The operation of the device is as follows: Assuming both doors areclosed, the parts will be in the position shown in Figs. 1, 2, 3, and,7. When the door i0 is opened the spring 28 using the plunger 2| as afixed abutment propels the plunger 25 outwardly, thereby shifting thethrust pin 24 to the left (as seen in Fig. 4) and causing the tube 8 tofollow its movement. In so moving the tube 8 pulls the cam slot 22 alongwith it and thereby moves the cam follower pin in the direction to turnthe sleeve i3 in a clockwise direction (Fig, 9), thereby causing thecollar pickup pins ll to engage the respective rods l2 and flip eachover to its grounding position. When the door I0 is swung back to closedposition the reverse action of the parts'takes place and the pick-uppins l8 are caused to engage the respective rods l2 to return them in apositive manner to inoperative position. With both doors now closedagain, it will be assumed that the door H is opened. The spring 28 nowuses the plunger as a fixed abutment and propels the plunger 2ioutwardly, This movement is transmitted to the rock-pin 20, which camsthe sleeve IS in a clockwise direction to flip the rods l2 to groundingposition through the action of the pick-up pins ll. When the door II isclosed the plunger 2| is pressed back against the tension of the spring29 and the pin '20 now cams the sleeve 18 counter-clockwise so that thepick-up pins l8 return the respective rods l2.

In case both doors l8 and II are open, the

closing of one door merely results in the wholeinternal assembly withinsleeve l3 sliding as an articulated unit, and no rotary motion of thesleeve l3 can take place because there is no fixed abutment againstwhich the spring 29 can react.

I claim as my invention:

1. A device for grounding electrical conductors, comprising a tube, twoplungers in said tube, a spring normally compressed between saidplungers to cause said plungers to project at opposite ends of said tubefor respectively contacting two doors, said plungers and spring having aminimum length when said doors, are closed and an aseaeas expandedlength when either door is opened, a grounding rod, and means Operatedby the expanding motion of said plungers, as one or the other of saiddoors is opened, (or moving said rod from an inoperative position to agrounding position.

2. A device for grounding electrical conductors, comprising a tube, twoplungers in said tube, a spring normally compressed between saidplungers to cause said plungers to project at opposite ends of said tubefor respectively contacting two doors, said plungers and spring having aminimum length when said doors'are closed and an expanded length wheneither door is opened, a grounding rod, and means operated by theretracting motion of said plungers as one or the other of said doors isclosed, for moving said rod from a grounding position to an inoperativeposition.

3. A device for grounding electrical conductors, comprising a tube, twoplungers in said tube, a spring normally compressed between saidplungers to cause said lungers to project at opposite ends of said tubefor respectively contacting two doors, said plungers and spring having aminimum length when said doors are closed and an expanded length wheneither door is open, a grounding rod, and means operating as a functionof the length of said spring and plungers for moving said rod from oneposition to another.

4. A device for grounding electrical conductors, comprising a tube, twoplungers in said tube, a spring normally compressed between saidplungers to cause said plungers to project at opposite ends of said tubefor respectively contacting two doors, said plungers and spring having aminimum length when said doors are closed and an expanded length wheneither door is open, a rounding rod, means operated by the retractingmotion of said plungers as one or the other of said doors is closed iormoving said rod from a grounding position to an inoperative position,and means rendering said last means ineflective if one door is closedwhile the other is open.

5. A device for groundin electrical conductors. comprising a. sleeve, atube in said sleeve and relatively slidable, means between said sleeveand tube for translating linear motion of said tube into rotary motion0! said sleeve, a grounding rod, means actuated by said sleeve forswinging said rod from one position to another and means arranged to beactuated by the opening or closing or an associated door to move saidrod from an ungrounded position to a grounded position during a dooropening movement and from a grounded position to an ungrounded positionduring a door closing movement.

6. A device for grounding electrical conductors, comprising a sleeve, atube in said sleeve and relatively slidable, means including a cam slotin said tube and a pin, for imparting rotary motion to said sleeve, agrounding rod, means actuated by said sleeve for swinging said rod fromone position to another, and means arranged to be actuated by themovement of an associated door I for causing said pin to move in adirection to means actuated by the opening 01' either door for causingsaid mounting means to move said rod away from said wall and intocontact with said conductor whereby I said conductor is grounded.

8. In an electron microscope, the combination of a wall forming aportion of a housing, oppor sitely disposed doors for said housing, agrounding rod, means mounting said rod for movement towards and awayfrom said wall, a current conductor in the path of movement of said rod,and means actuated by the closing or one door after the other door isclosed for causing said mounting mean to move said rod out of contactwith said conductor and into contact with said wall.

9. A device for grounding electrical conductors,

' comprising a sieeve, a tube relatively slidable in of said sleeve foroperating said turning means to cause said rod tomove to a groundingposition, and means arranged to be actuated by the opening of a door atthe other end of said sleeve for operating said turning means to causesaid rod to move to the same grounding position, said last actuatingmeans being rendered ineffective when the first actuating means hasfunctioned.

FRANK E. RUNGE.

